So this guy walks into a chat room

[Cookie]

I've been slowly testing this bike down looking for the remaining small burble.
So far it has been tested as such
New plugs and compression, 150, to 155 in all holes.
I did that vacuum test and got number three to run, but I'm not sure perfectly at idle.
I synced the carbs, that helped a bit.
Swapped carbs to the recently rebuilt 75s from the guy in San Jose. Now all holes are good and hot but still a burble.
Watered the ignition system at night and tested it with a firing pen. All firing, no leaks apparent, no change when water hits coils.
Tested with a propane torch for leaks.
Checked the advance.
Checked the timing.
Next up will be to sync the new carbs and see what I have.

[Fred Camper]

Wow, seems like a persistent burble. Not sure the new carb sync will help, but worth a try. Maybe she just needs some miles on her as you have been avoiding her of late. Let us know what you learn Cookie.

[Hoosier Daddy]

Tested with a propane torch for leaks.

All the threads I have read on here this is the first time I have seen this referanced. I used that method back when I was and Auto Tech to troubleshoot for vacuum leaks on carburated engines. Especially hady around intake manifolds.
Then when computer controls and fuel injection came along it kind of went by the wayside because the O2 sensor would pick it up and the adjust to mask the increase in fuel mixture.
Was going to try and adjust my idle mixture with it once the engine was back together. On a single carb engine, you'd give her a quick shot down the carb and the idle should jump about 50-80 rpm when the mixture was right.... but can't think how I can isolate it to individual carbs on these GL engines, maybe more of an overall test of all four down the plenum I guess.

[Cookie]

I don't see how either since the plenum blends. I think I have an intermittent ignition cut out. Since I have tried bypassing the switch it isn't power, I can see some fluctuation in the pen tester followed by a rattle in the primary. It is so fast it is hard to isolate.
I may try bypassing the ignition leads from pickup to coil and if I can't find it there see if a friend still has an oscilloscope.
In the old days I just would have plugged this sucker into the tune up machine and I'd be able to see where my problem was, this is pretty primitive.

[Hoosier Daddy]

see if a friend still has an oscilloscope.
In the old days I just would have plugged this sucker into the tune up machine and I'd be able to see where my problem was, this is pretty primitive

Didn't think any scopes were still around! GOD things were so much easier then! You could actualy SEE what was going on with your coils spark, and points and condensers. Sounds like you know your way around one, so this should bring back some memories. Looks like the gap on #4 in the firing order is a little close.

[Cookie]

Some of us are old people...I was just out bending an 8mm for setting carbs and making a cut down air cleaner to use for testing, no room to get around a stocker. It occurs to me I have not really tested the resistor or the cut off circuit as well as the signal wires from the electronic ignition. Any of that old wiring could be the problem.

[Hoosier Daddy]

I am with you.. well close anyways.
When I started wrenching for a living, that's how we did it and I could handle it. Then came HEI ignitions, then computer controls, and they took away the carbs Ughh! What a nightmare in the begining!
So I stuck with 12v electrical systems, Brakes, suspension, and alignments. Let those "Drivability" guys worry about the ECM's griefs

[Cookie]

I like the new electronics, I have very little trouble with my BMW or Subaru, normal stuff like oxy or cam sensors. Don't even ask about my 74 Volvo, that car was not ready for prime time.
Tomorrow I'm going to run some new wires on this bike, all that stuff is 30 years old and any one of them could be broken or have a little bit of a bad connection. When you think of it it's only a few wires. No rush, I have a few other bikes I can roll out of the garage, I'll ride the last LTD to work Tuesday if I'm not happy with yellow.
Tomorrow I have a mandatory furlough day which coincides with a wife day off so not much bike stuff in store.
With the modern computers you plug in the reader and it gives you a number. Then you find out it means something like catalyst below efficiency and you get to figure out what that really means, and it often could be two or three things, bad sensor, exhaust leak, bad cat, etc.
That is almost as annoying as this crap.

[Hoosier Daddy]

Ageed.
Ageed.
And Ageed.

[Cookie]

My wife is at work so I get to work on this one a bit more. The first thing I did was to change the air cut off valve this time as one of the o rings was too flat but was all I had at the time, I'm pretty sure that gave me a tiny air leak as the adjuster was not responding, now that one works.
The best thing I've done so far was to bend a wrench and put a little bolt handle on it that works great on the synchronizing screws, don't know why I didn't make one of those three years ago.
I think number three is still a little weak and I still have that little burble that makes my primary rattle. When I get back from errands I may swap the wires for that coil to see if the problem follows that wire.
After that I may just change over to Dyna coils that are on the shelf.

[Fred Camper]

Well, you are going to use those Dyna Coils on something anyway...

[Cookie]

Yup,

I swapped plugs wires with little change so I may as well try the Dynas. I have a set of V8 plug wires here to make wires. Wiring them in will also eliminate some of the old wiring and the resistor, I've been cleaning and wiggling connections with no change.
Here are the carbs I swapped in.
And making up a coil set.

[Hoosier Daddy]

[TAZA2]

you sure he said it ran when he put it away? Can't afford drugs, Have the honda monkey on my back, opps need that part and that part.

[Cookie]

This does feel a bit like a monkey, as soon as you find the problem you go, "rats, is that all it was?"